I am amazed that this thread is still alive.
Ammonia and nitrite are acutely toxic. Nitrate is lowly toxic to fish, and slightly more toxic to invertebrates. This is why reef tanks must have very low nitrate level to thrive. Fish can tolerate hige nitrate level for a short time, but chronic exposure to elevated nitrate level can compromise fish immunity leading to suceptability of deseases. So the goal for keepig healthy fish is to maintain as low nitrate level as practicable.
Nitrate is not the only waste of concern. Nitrate is an indicator of general water quality. So if nitrate is high, it is an indicator that other cogenerated wastes such as phosphate, potassiam, other nutrients and organic matters are also high. No one talks about phosphate cycle or the toxicity of phosphate and other wastes which are not harmless at elevated levels. There are also complex organic matters in the water that gives the water fishy smell. Salt water folks use protein skimmer to remove organic matters. Most FW don't know or care.
You can't be lazy if you want to maintain canisters the right way. It is actually more time consuming to clean a canister than a HOB, sponge or sump filter, just not as frequently as mandatory for other filters. Other filters will get clogged up and stop working if you don't clean them frequently. Canisters allow you get lazy to postpone cleaning, but it is bad for water quality and the fish.
The popularity of canister is just great marketing, not fundamentally more sophisticated than other filters.
